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POContours / Connected components in OpenCV 2.4.4
 

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  1. POContours / Connected components in OpenCV 2.4.4
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    <p>I'm currently working on an image with a lot of detected contours. My goal is to narrow down the number of contours to end up with only the one I'm looking for. For that I conduct a bunch of tests based on area and bounding box.</p> <p>For now I do after every step a <code>drawContours</code> for the contours that I want to keep followed by a <code>findContours</code>.</p> <p><strong>My problem is</strong> that I would like to do <code>findContours</code> only once and then just erase the contours I don't want, is this possible?</p> <p>Current way :</p> <pre><code>Mat src; Mat BW; src = imread("img.bmp", 0); if( src.channels() &gt; 1) { cvtColor(src, src, CV_BGR2GRAY); } threshold(src, BW, 100, 255, CV_THRESH_OTSU); imshow( "Tresh", BW ); Mat dst = Mat::zeros(src.rows, src.cols, CV_8UC3); Mat dstP = Mat::zeros(src.rows, src.cols, CV_8UC3); Mat dst1 = Mat::zeros(src.rows, src.cols, CV_8UC3); Mat dst2 = Mat::zeros(src.rows, src.cols, CV_8UC3); vector&lt;vector&lt;Point&gt; &gt; contours; vector&lt;Vec4i&gt; hierarchy; findContours( BW, contours, hierarchy, CV_RETR_CCOMP, CV_CHAIN_APPROX_SIMPLE ); for( int i = 0; i &lt; contours.size(); i++ ) { Scalar color( rand()&amp;255, rand()&amp;255, rand()&amp;255 ); drawContours( dst, contours, i, color, 2/*CV_FILLED*/, 8, hierarchy ); } /// Test on area ****************************************************************** for( int i = 0; i &lt; contours.size(); i++ ) { if ( contourArea(contours[i], false) &gt; 100 &amp;&amp; contourArea(contours[i], false) &lt; 200000) { Scalar color( rand()&amp;255, rand()&amp;255, rand()&amp;255 ); drawContours( dst1, contours, i, color, CV_FILLED, 8, hierarchy ); } } /// Next test ********************************************************************** cvtColor(dst1, dstP, CV_BGR2GRAY); findContours( dstP, contours, hierarchy, CV_RETR_CCOMP, CV_CHAIN_APPROX_SIMPLE ); </code></pre> <p>etc</p> <p>Wanted way :</p> <pre><code>if ( contourArea(contours[i], false) &lt; 100 &amp;&amp; contourArea(contours[i], false) &gt; 200000) { contours.erase(i); // Doesn't work } </code></pre> <p>Does anyone now how to erase those contours?</p> <p>PS : I don't care about inner contours, I want all of them to go trough my tests.</p> <hr> <p><strong>EDIT</strong>, the solution (pointed out by limonana) is : <code>contours.erase(contours.begin()+i);</code></p>
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    1. USThom
    1. USThom
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      1. POContours / Connected components in OpenCV 2.4.4
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      1. POContours / Connected components in OpenCV 2.4.4
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    1. COMay be you can create a new countour structure and keep adding those which pass your test.
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      1. POContours / Connected components in OpenCV 2.4.4
      1. USAbid Rahman K
    2. COWhy doesn't it work? Where is the rest of the data being kept?
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      1. POContours / Connected components in OpenCV 2.4.4
      1. USBoyko Perfanov
 

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